This application relates to an improved system for opening and closing garage doors.
All systems which are currently known to the inventor to be in use for opening and closing garage doors, particularly in the commercial context, rely on springs and/or counter weights to balance the door. There are a great many disadvantages to such current systems. Many of these pertain to very substantial maintenance costs. These include spring breakage, cable stretch and drum slippage on the spring and counter weight systems, the imposition of a constant force on the garage door components, the upward bowing of the ends of the door, and the weight of the components. Ongoing maintenance includes frequent lubrication and other associated and time consuming maintenance.
A significant disadvantage to current systems is that they require substantial headroom above the door opening itself. Where a limited ceiling height is available, this obviously limits the permissible height of the door opening and thus the height of vehicles that can use the garage.
As well, current systems have a relatively low cycle life in the commercial context.
The safety factor of current installations is also relatively low.
It is against the above background that the present invention arises.
Applicant is aware of the following. U.S. patents which pertain to current garage door opening and closing systems:
U.S. Pat. No. 1,954,813, Harris, Apr. 17, 1934
U.S. Pat. No. 2,747,864, Miller, May 29, 1956
U.S. Pat. No. 2,909,178, Lawick, Oct. 20, 1959
U.S. Pat. No. 3,353,299, Castonguay, Nov. 21, 1967
U.S. Pat. No. 3,478,469, Estes, Nov. 18, 1969
U.S. Pat. No. 3,633,313, Lafontaine, Jan. 11, 1972
In addition, French Patent FR-A-2 726 855 teaches a garage door opening/closing system comprising a garage door having top, bottom, first and second sides and having a series of rollers associated with the first and second sides. A pair of door rails at the first and second sides of the door for receiving the rollers for movement of the door along the rails in a door opening path is discussed. There is also provided a central guide rail extending outwardly from the plane of a closed position of the door from a position above the top of the door and a trolley mounted on the central guide rail for movement along the guide rail. At least one member for hinge connection between the door and the trolley is provided wherein the member is extending from a midpoint of the top of the door perpendicular to the top of the door along the service of the door. The reference further requires two sets of counterweights required to balance the door in order to enable it to function. The counterweights form an integral part of the teaching of that reference and the arrangement for lifting the door would have little chance of operating in the absence of those counterweights.
The invention provides a garage door opening/closing system comprising a garage door having top, bottom and first and second sides and having a series of rollers associated with the first and second sides; a pair of door rails at the first and second sides of the door for receiving the rollers for movement the door along the rails, in a door opening path; at least one hinge part mounted on the door intermediate the first and second ends; a central guide rail extending outwardly from the plane of a closed position of the door from a position above the top of the door; a trolley mounted on the central guide rail for movement along the guide rail, the trolley for operative connection to at least one hinge part; at least one cable drum having a pair of cables thereon operatively associated with the trolley for moving the trolley along the central guide rail; and operator means operatively associated with at least one drum for driving at least one drum.